PRECISION TUNING OF A PHASE-CHANGE RESISTIVE ELEMENT

The present invention comprises a method and structure for programming an on-chip phase-change resistor to a target resistance. Using an off-chip precision resistor as a reference, a state-machine determines a difference between the resistance of an on-chip resistor and the target resistance. Based upon this difference, the state machine directs a pulse generator to apply set or reset pulses to the on-chip resistor in order to decrease or increase, respectively, the resistance of the resistor, as necessary. In order to program the resistance of the phase-change resistor to a tight tolerance, it is successively reset and set by applying progressively decreasing numbers of reset pulses and set pulses, respectively, until the number of set pulses is equal to one and the target resistance of the on-chip resistor is reached.